Chlorinated silizane polymers, process for their preparation, process for the preparation of silicon nitride-containing ceramic materials

摘要

The invention relates to novel chlorine-containing silazane polymers, to their preparation, their further processing to ceramic material containing silicon nitride, and this material itself. In order to prepare the chlorine-containing silazane polymers, oligosilazanes of the formula (I) IMAGE in which a0, b/=0 and n is about 2 to about 12, are reacted with at least one of the chlorosilanes Cl2R4Si-CH2-CH2-SiR4Cl2, Cl3Si-CH2-CH2-Sir5Cl2, R6SiCl3 or R7SiHCl2 at 30 DEG C. to 300 DEG C., where, independently of one another, R1 and R2=H, C1-C6-alkyl or C2-C6-alkenyl, R3, R4, R5, R6 and R7=C1-C6-alkyl or C2-C6-alkenyl and where if b=0 the reaction with R7SiHCl2, if R7=C1-C6-alkyl and none of the other chlorosilanes is present, is to be excluded. The chlorine-containing silazane polymers according to the invention can be converted by reaction with ammonia into polysilazanes, which in their turn can be pyrolyzed to form ceramic materials containing silicon nitride.